Program Speaker : Joe Kast - Gem Stone Travels

by Nancy Attaway

Paul Hlava scheduled gem dealer, Joe Kast, who described his travels in Asia to purchase rubies and sapphires. Joe also related his gem travels in Colombia, where he bought emeralds. Joe Kast resides in Albuquerque. Paul met Joe at the AGTA Show a few years ago during the February “event” in Tucson.

Joe began by passing around two large cushion cut oval sapphires for members to view. One sapphire showed a rich, dark royal blue color. The other one exhibited a very light blue hue with sparkle made by the extra attention paid to faceting. Joe remarked that the darker colored sapphire was priced at $2,400 per carat wholesale, while the lighter colored sapphire was marked at $200 per carat wholesale. The big difference in price was duly noted by the audience. Both gems had attributes that were admired by everyone, but Joe’s point was that color was the key. The deeply saturated royal blue hue in sapphire commands the higher prices.
Joe displayed several large crystals of sapphire that were blue-gray in color and not at all gemmy. These showed distinct crystal faces of the hexagonal crystal system of sapphire with some terminations. Joe also displayed two Colombian emerald crystals in matrix with pyrite. One crystal in one specimen had formed naturally in place. The other was glued into the matrix.

Joe began his career in gems around 1988. Prior to that, he was a licensed chiropractor for 28 years in northeast Pennsylvania. One of his patients was a gemcutter, who further inspired Joe’s interest in gems.

Joe showed several poster-sized photographs that he took of the mining areas in Thailand. One depicted several miners sifting for rubies and sapphires in a stream bed, standing knee-deep in water. Nearby, mine holes were dug over 30 meters deep with no shoring. Another photo showed the famous open-pit, hard rock mine at Kanchanaburi that is owned by a Chinese. Joe remarked that sapphires from Kanchanaburi are dark.

Joe explained first his gem buying trips to Thailand. He arrives in Bangkok, usually on Thai Airlines, which takes about a day’s time to travel from San Francisco or Los Angeles. Sometimes, he takes Cathay Pacific Airlines to Bangkok. He uses an American consolidator for his trip planning and logistics.

Joe described the food in Thailand as somewhat spicy to very spicy. A fork and a large spoon is used.

Joe said that he works with a gemstone broker in Bangkok, who he has come to know and trust after doing business with him for several years. The broker contacts the cutting houses, which are Chinese owned. The gemcutters are all Thai. Joe looks through between 200 and 300 stones in gem papers from 9:45 am until 3:15 pm, when the light starts to change. Joe remarked that once the light of day changes, the color of the stones are affected and will appear different from the morning light. Also, your eyes become fatigued.

Joe explained that the cutting houses worked on a 10% profit margin, a very tight margin. The owners preformed all of the rough and then turned it over to the Thai cutters. The cutters were paid by the carat weight, which is why you see so many large bellied gemstones. Cut stones are placed in the inventory and sent by a runner to the broker. Runners are usually relatives or friends of the cutters who represent the cutters.

Joe described his gemstone purchasing in the following manner. After he selects the stones that he is interested in buying, Joe goes down the list and asks the price for each stone. The runner (remember that he represents the cutter) replies with a very high price to see if he will accept it. Joe usually counters with a much lower price. This banter goes back and forth between the runner and the buyer for each stone. The runner calls the boss back at the cutting house for each counter offer. Joe usually purchases 65% of the stones on his list. One single deal may take only 15 minutes, while other deals may take an entire day of price haggling.
Joe remarked that the cutting houses turn their gemstone inventory over as quickly as they possibly can. Each gem paper that holds a stone is coded in Thai, noted on the cover. Joe pays in (U.S.) dollars to the broker, who then pays the runner in the local Thai currency. Often, wire transfers are used between banks.

Joe mentioned that many of the gemstones he buys in Thailand need to be re-cut to improve the optics and make them more symmetric in overall shape. Joe buys Burma ruby, ruby from Madagascar, and Thai sapphire. He mentioned that ruby from Burma fluoresces under ultraviolet light, but ruby from Madagascar does not.

Joe always faxes to the U.S. commercial customs the list of the gems that he intends to purchase, and he performs this task before he leaves the gem broker in Bangkok. There is no duty paid on loose gems into the United States. Joe is insured with Jewelers Mutual.

Joe usually ships by Federal Express to his customers and insures parcels at cost. He has also shipped by registered mail. He has had one loss by Federal Express and had two losses from registered mail in the United States. His insurance covered them all.
Joe describes Bangkok as a very polluted city. Many commuters use the old two-stroke engines on motor bikes. The temperature hovers around 92 degrees F during the day and falls to the low 80’s at night. He said that the fruit there is most tasty. He thinks that Thai people are very nice, and he feels very safe there.

Joe next described his trips to Sri Lanka, which requires another 24 hours to travel. Joe said that he does not fly on Sri Lankan airlines, as the civil war there, between the Hindu Tamils and the Buddhists, has made local air travel too violent. Joe does not travel on Indian airlines, for similar reasons. He travels on Thai airlines from Bangkok to Colombo, which takes longer in travel time and has several layovers.

Joe remarked that the gem dealers in Sri Lanka were all Muslims. He said that establishing contracts with these dealers was most important. He remarked that there was no electricity at night in Colombo. As a result, Joe said that he did not stay in small hotels but stayed in the large hotels, which own generators. The large hotels, however, charged expensive rates.

Joe said that he has stayed in the home of his Muslim contact. The home had marble floors, and no shoes were worn inside the home. The Muslim homeowner employed several servants. Servants were paid $30 to $50 per month there. In contrast, gemcutters in Colombo were paid $90 per month.

Joe remarked that the pace of life in Sri Lanka was much slower than the pace set in Bangkok, Thailand. He also said that there were less gems in Colombo to view. He stated that the cutters in Sri Lanka mostly cut ovals and cushion cuts, and that most Sri Lankan sapphires were heat-treated to enhance the blue color. Heat-treatment removed the silk (melts the rutile needles) and brightens the stones. Not all sapphire rough was guaranteed to change color under heat-treatment.

Joe said that he usually dressed casually while overseas in Asia. He recommended such attire to better blend in with the locals. He advised that one should not stand out any more then is absolutely necessary.

Joe then told of his gem buying travels to South America for emeralds. His flight took him to Santa Fe de Bogota in Colombia, which lies at an elevation of 8500 feet. The daytime temperatures there ranged between 60 to 70 degrees F. A gem broker picked him up at the airport, and he was flown by military helicopter to the Muzo emerald mine. The Muzo mine is situated in the Andes Mountains, northeast of Bogota, which is lower in altitude, more humid, and warmer. Both the Chivor mine and the Cosquez mine, noted emerald localities, are located near the Muzo mine.

Joe said that the people there spoke an elegant Spanish dialect and have been very friendly. He said that everyone in Bogota dressed formally. The food was bland, and a lot of potatoes were served. Joe never ventured out at night alone. He advised to be very careful when taking a taxi and always had one or two other people accompanying him when he rode in a taxi.

In Colombia, gem brokers were separated from the gemcutters. Sometimes, the brokers worked directly with the cutters. Joe said that he often had to compete with gem buyers from other countries for Colombian emeralds. The price of emeralds fluctuated with the supply and the demand. Not much in fine emerald goods was available when he was there.

Joe explained that all emeralds were oiled. He said that nitric acid was used to clean the rough emeralds, and then the crystals were oiled in a heated vacuum. Any kind of oil might be used, but cedar oil and balsam oil were usually the ones used. Joe stated that he has even seen 3-in-1 Oil even used in emerald treatment.

Joe said that the Colombian government office checked and sealed the bags of emeralds he bought, and then a government representative brought the purchased parcels to the airport via Brinks delivery. Official government agents even escorted him to the plane. Joe remarked that soldiers armed with semi-automatic weapons guarded the airport, and that their presence was everywhere. Joe also remarked that no pictures of the soldiers was allowed to be taken, and he said that each emerald mine employed its own army of guards.

Joe explained that emeralds have been mined in Colombia for over 1,000 years. The mine tunnels dug into the black shale mountains now have had air pipes installed to bring in fresh air from the outside. Many tunnels have been dug, and some tunnels have been sectioned out and even gated. The host rock for emeralds is a black shale with white calcite veins. Miners follow the calcite veins to locate the emerald crystals. Sulfuric acid made the air in the mines most foul, and the sulfuric acid fumes were extremely hazardous.

Paul Hlava said that pyrite is associated with Colombian emeralds. Paul explained that the black rock is a carbonaceous shale that has been brecciated. Carbonaceous means that it contained carbonate minerals. Calcite is the most common, but dolomite, siderite, aragonite, rhodochrosite are also possibilities. Paul said that Muzo emeralds are formed hydrothermally and are found in calcite cavities. Iron is “sucked” from the shale and reacts with sulfur-rich ore fluids to form pyrite, but the chromium remains. Chromium enters the beryl crystals and causes the green color. Muzo emeralds, therefore, show a high color saturation of green.
Paul further explained that pyrite (yes, pyrite) helped to make the Muzo emeralds so beautifully green. He said that emeralds from the Muzo District of Colombia are prized for their pure, INTENSE, chromium-green color. Paul remarked that Dr. Terri Ottaway of the Royal Ontario Museum wrote an article, where she explained the geological cause of this pure color. Paul then related the “meat” of her article so most laymen could understand the process.

    The article stated that Muzo emeralds are hosted in Cretaceous aged (65 to 135 million years old), carboniferous, and carbonaceous (carbon-bearing and calcite-bearing) shales, as well as similar sedimentary rocks. These shales are full of “dirt”, in addition to the carbon (which may actually be fine graphite) that stains black everything it touches. By “dirt” Paul meant a host of trace elements, such as iron (Fe), chromium (Cr), vanadium (V), manganese (Mn), cobalt (Co), zinc (Zn), copper (Cu), rare-earth elements (REE), et hoc genus omni. Some of these, such as Cr, Fe, and Mn, fit into the structure of beryls. Chromium in the shales is most welcome, as it provides the emerald-green color that we want to see in emeralds. Iron and the others are unwanted, because they “taint” the color. Because iron is so much more abundant than all the others combined, it is considered to be the main problem.

    As in most mining districts, the Muzo saw a number of episodes of mineralization. Mountain building tectonics fractured the rocks and hydrothermal (hot and watery) fluids intruded along these fractures. These fluids not only introduced mineral material, but they also reacted with the stuff in the shales. The PRIME reaction occurred when the very sulfur-rich early fluids “sucked” most of the iron from the shales and deposited beautiful pyrite crystals in the veins (along with quartz, feldspar, and calcite crystals). Luckily, the beryllium (Be) needed for emerald came along in some of the last episodes of activity.
Paul said that this situation was very fortunate, because the iron was tied up and could not discolor the emeralds. Even later episodes might have broken and/or altered earlier emeralds into worthless grunge. Paul said that one may ask why the early sulfur did not “suck up” the chromium along with the iron. Paul explained that chromium has a very low propensity of forming sulfides. Chromium-sulfides do occur, but they are rare and found in situations where lots of chromium and sulfur are forced together with little or no chalcophile (sulfur-loving) elements, like iron, present.

Paul said that the next time you see a matrix specimen of Muzo emeralds side by side with lots of pyrite crystals, you should thank those pyrites for helping to make the emeralds so exquisitely pure, intense, emerald-green!

For those interested in reading the article by Dr. terry Ottaway, her article, “Formation of the Muzo Hydrothermal Emerald Deposit in Colombia” was published in Nature, Volume 369, pages 552-554. Dr. Terry Ottaway is the Assistant Curator and Gemologist of the Department of Earth Sciences of the Royal Ontario Museum. The article was authored by her and T.L. Wicks, F.J. Bryndzia, L.T. Kyser; T.K. and Spooner, E.T.C. (1994).

Thank you, Joe Kast, for a fascinating talk of your gem travels. Many of us wished that we could have been with you to see all you that had seen. Such remarkable experiences you shared! Thanks also to Guild Vice-President and Guild Mineralogist, Paul Hlava for pointing out and further explaining the importance of pyrite in Muzo emeralds.